A mechanical casing running tool (“CRT”) is a multi-purpose casing running tool. Utilized on rigs equipped with top drives, CRTs are capable of casing-drilling and/or running. CRTs are available in various models from several manufacturers, but in combination with the top drive, they generally all perform the following functions: (1) makeup or breakout casing connections, (2) reciprocate casing strings, (3) fill casing strings with drilling fluid, (4) circulate drilling fluid through casing strings, and (5) rotate casing strings.
Without the convenience of a CRT to perform all of these operations, the multi-faceted process of casing-drilling and/or running typically requires a full complement of tools. In that sense, the use of a CRT can generally reduce cost, non-productive time (“NPT”), overall rig-time, and the number of safety hazards by eliminating the need to rig up and rig down multiple tools. Additionally, certain CRTs are equipped with pipe-pickup mechanisms that manipulate single joint elevators (“SJE”). By pivoting its pipe-pickup mechanism away from the well center (i.e., link-tilt), the CRT can utilize its SJE to latch onto a single joint of casing presented at the V-door. Then, by retracting the pipe-pickup mechanism as the top drive and CRT are hoisted into the derrick, the CRT can transport the single joint from the V-door to well center.
CRTs that are not equipped with pipe-pickup mechanisms, however, are incapable of retrieving single joints from the V-door. The lengths of these CRTs, once rigged up to the rig's top drive shaft, are such that the lower portions of the CRTs extend below the lower eyes of the rig bails that are used during drilling operations. Attaching a SJE to the rig bails, which are pivotally powered to reach out towards the rig's V-door, would be one way to retrieve single joints; however, attaching a SJE to the lower eyes of the rig bails results in interference between the CRT and the SJE, so this is not a feasible solution. In order to retrieve single joints from the V-door, it is common to utilize slings suspended from the top drive to attach a SJE. The process of rigging up, using, and rigging down pickup slings not only delays the job considerably, but it requires unsafe manual intervention to transport SJEs from well center to the V-door for every joint in the string, of which there may be several hundred. Some conventional bail extensions may be directly pinned to the rig bails, thereby eliminating the need to rig down the bails. However, there are serious disadvantages with this approach for picking up single joints. These bail extensions are rated for full string weight (e.g., 150-350 tons), which results in these extensions being heavy and expensive. Further, the pivoting connection of the extensions to the rig's drilling bails does not allow these bail extensions to reach the V-door in all cases. Although there are adjustable-length versions of these bail extensions, the same benefits and disadvantages apply.
Adjustable-length single joint links are also available. These single joint capacity elevator links are adjustable in length. The telescopic design allows the links to extend past the lower portion of the CRT, thereby providing an attachment point for a SJE and spanning the distance to the V-door. These adjustable-length single joint links are capable of being interfaced to the rig's link-tilt mechanism in the same manner as the drilling bails, thereby providing a means to manipulate these single joint links to pick up casing from the V-door. One drawback, however, is the fact that this product replaces rig bails, necessitating both the time-consuming, costly, dangerous rig down of the rig bails and the rather time-consuming rig up of these single joint links.